Film capacitors having both a self-healing function and a self-protection mechanism are disclosed in Patent Documents 1 through 4, for example.
The film capacitor disclosed in Patent Document 1 has a pair of capacitor electrodes which confront each other with a dielectric film sandwiched therebetween. At least one of the capacitor electrodes is formed by metal evaporation, and is divided into equally spaced or arbitrarily spaced intervals in the longitudinal direction of the film by a plurality of insulating grooves, thereby providing a plurality of segmented electrode banks. The segmented electrode banks comprise electrodes provided by a network of insulating grooves with a plurality of narrow current paths left therebetween.
The capacitor electrodes sandwiching the dielectric film serve as a metalized film having 2 to 20 independent small electrodes arrayed in the longitudinal direction of the film and a plurality of independent small electrodes arrayed in the transverse direction of the film. The metalized film is rolled into a roll, and metal is thermal-sprayed to opposite end faces of the roll to form terminal electrodes, thus producing a capacitor element. One or more capacitor elements are encased into the film capacitor.
The film capacitor disclosed in Patent Document 2 comprises a dielectric film and a metal-evaporated electrode disposed on the dielectric film. The metal-evaporated electrode has a plurality of divided electrodes arrayed in longitudinal and transverse directions thereof. The divided electrodes are segmented by non-electrode margins, and margin fuses having a fuse function are disposed in the margins. The margin fuses are superposed over margin fuses on upper and lower confronting electrodes.
The film capacitor disclosed in Patent Document 3 is a capacitor sheet which comprises a dielectric capacitor sheet having a metal thin film thereon and rolled into a capacitor roll in the traveling direction of the dielectric capacitor sheet. The film capacitor includes a metalized region which includes the metal thin film with divisions therein. The metal thin film includes partial divisions formed in the transverse direction to the traveling direction of the capacitor sheet.
The film capacitor disclosed in Patent Document 4 includes a pair of evaporated electrodes having divided electrodes connected parallel to each other through fuses and extending from a substantially transversely central region toward insulated margins in an effective electrode area providing a capacitance. Since the fuses and the divided electrodes are disposed closely to the insulated margins where reduced currents flow at positions away from components plated by thermal-sprayed metal, the heat produced by the fuses is reduced to lower a temperature rise.
Patent Document 1: Japanese Patent No. 3710873;
Patent Document 2: Japanese Laid-Open Patent Publication No. 09-199371;
Patent Document 3: Japanese Laid-Open Patent Publication No. 2002-504747 (PCT); and
Patent Document 4: Japanese Laid-Open Patent Publication No. 2004-134561.